fix: getting app exe path when using PublishSingleFile

[Basewq]

PR Details

Use PlatformFolders.ApplicationExecutablePath instead of Assembly.GetEntryAssembly().Location

https://learn.microsoft.com/en-us/dotnet/core/deploying/single-file/overview?tabs=cli#api-incompatibility
Under 'API incompatibility' Assembly.Location is not available with single file deployment.
https://learn.microsoft.com/en-us/dotnet/api/system.environment.processpath?view=net-8.0
Environment.ProcessPath can be used as a fallback, but do note that even that can return null.

Related Issue

Fixes #2304 where Icon is set via GameContext.ProductLocation

Also fixes the super secret LeftCtrl + C+ F1 screenshot command in PublishSingleFile.

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My change requires a change to the documentation.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have built and run the editor to try this change out.

[Eideren]

Thanks !